Full text of "Tyrannosaurs from the Late Cretaceous of western Canada"

See other formats

TYRANNOSAURS FROM THE
LATE CRETACEOUS OF
WESTERN CANADA

By Dale A. Russell

Ottawa, 1970

Queen’s Printer for Canada
Ottawa, 1970

Cat. No.: NM95-8/1

RESUME

Le nom de famille Tyrannosauridae s’applique a un groupe de grands dino-
saures theropodes qu’on trouve dans les sediments du Cretace superieur, a
I’interieur de l’Amerique du Nord et en Asie centrale. On reconnait qu y Alberto¬
saurus Osborn est en fait un synonyme plus ancien de Gorgosaurus Lambe, et
les especes designees comme Gorgosaurus sont reclassees sous l’ancien genre.
Albertosaurus sternbergi (Matthew et Brown) et A. Arctunguis Parks sont des
synonymes plus recents <XA. libratus (Lambe) et d'A. sarcophagus Osborn res-
pectivement. Un deuxieme genre de tyrannosaure, Daspletosaurus torosus , qui
represente aussi une nouvelle espece, a ete reconnu pour la premiere fois dans les
sediments des formations Oldman et Edmonton inferieure.

Le crane du tyrannosaure etait essentiellement acinetique, bien qu’il ait
pu se produire un certain mouvement mediolateral dans la region posterieure
de chaque moitie du palais. Les elements medians ventraux de la boite cranienne
et les apophyses paroccipitales contenaient des sinus qui les occupaient presque
entierement. On a compare plusieurs specimens d'Albertosaurus libratus afin
de decouvrir dans les proportions des elements du squelette, les differences qui
sont liees a la taille du sujet. On s’est aper^u que les extremites (main, jambe
inferieure, pied et queue) etaient relativement plus grandes chez les individus
jeunes, alors que les elements des regions plus centrales de 1’organisme (ceintures
de membres, vertebres presacrees et cotes) etaient relativement plus importants
chez les adultes. On attribue la grande frequence d’humerus malades aux accidents
causes par la disproportion entre les bras relativement fragiles et le tronc massif
et puissant.

On connait la presence de tyrannosaures dans plusieurs secteurs du cretace
superieur de PAlberta, soient;

Formation Oldman: Albertosaurus libratus
Daspletosaurus torosus

Formation Edmonton inferieure: Couche A:

Albertosaurus sarcophagus

Formation Edmonton inferieure: Couche B:

Albertosaurus sarcophagus
Daspletosaurus cf. (D. torosus)

Formation Edmonton superieure (correspond a la formation Lance)
cf. Tyrannosaurus rex

SUMMARY

The family group name Tyrannosauridae is applied to a group of large
theropodous dinosaurs from late Cretaceous sediments of the interior of North
America and central Asia. Albertosaurus Osborn is recognized as a senior
synonym of Gorgosaurus Lambe, and species formerly referred to Gorgosaurus
are transferred to the former genus. Albertosaurus sternbergi (Matthew and
Brown) and A . arctunguis Parks are junior synonyms of A. libratus (Lambe)

and A. sarcophagus Osborn, respectively. A second genus of tyrannosaur,
Daspletosaurus torosus new genus and new species, is recognized in Oldman and
lower Edmonton sediments for the first time.

The tyrannosaur skull was essentially akinetic, although some mediolateral
movement may have taken place in the posterior region of each half of the
palate. The median ventral elements of the braincase and paroccipital processes
are filled with sinus cavities. Several specimens of Albertosaurus libratus were
compared in order to discover differences in the proportions of skeletal elements,
which correlate with the size of the individual. It was found that the extremities
(manus, lower leg, pes, and tail) are relatively larger in more immature indi¬
viduals, while elements in more central areas of the body (limb girdles, presacral
vertebrae, and ribs) are relatively larger in adults. The high incidence of patho¬
logic humeri is attributed to accidental damage of the relatively fragile forelimb
by the massive and powerful body.

Tyrannosaurs are known to occur in several horizons of the late Cretaceous
of Alberta as follows:

Oldman Formation:

Albertosaurus libratus
Daspletosaurus torosus
lower Edmonton Formation, Member A:

Albertosaurus sarcophagus
lower Edmonton Formation, Member B:

Albertosaurus sarcophagus
Daspletosaurus cf. D. torosus
upper Edmonton Formation (Lance equivalent):
cf. Tyrannosaurus rex

Contents

RESUME, v

SUMMARY, V

INTRODUCTION, 1

Family tyrannosauridae, 2

ALBERTOSAURUS, 4

Albertosaurus libratus , 5
Albertosaurus sarcophagus, 10

DASPLETOSAURUS, 13

Daspletosaurus torosus, 13
Daspletosaurus cf. D. torosus , 18

TYRANNOSAURUS, 18

cf. Tyrannosaurus rex , 18

TYRANNOSAURS NOT KNOWN TO OCCUR IN CANADA, 20
Albertosaurus lancensis, 20
Tarbosaurus bataar, 20

TABLES OF MEASUREMENTS, 21

REFERENCES, 29

List of plates

I Albertosaurus libratus , skeleton of immature individual, 31
II Albertosaurus libratus , skeleton of adult individual, 32
III Daspletosaurus torosus, dorsal view of forelimb elements, 33
Daspletosaurus torosus, ventral view of forelimb elements, 34
vii

List of figures

1. Albertosaurus libratus, skull in lateral aspect, 5

2. Albertosaurus libratus , median elements of skull roof, 6

3. Albertosaurus libratus , restoration of hatchling, 8

4. Albertosaurus libratus , lower half of braincase in sagittal section,

5. Cranial nerve exits in laterosphenoid of Albertosaurus | and
Daspletosaurus , 13

6. Daspletosaurus torosus, skull in lateral aspect, 15

7. Daspletosaurus torosus , skull in dorsal aspect, 16

8. Daspletosaurus torosus , palate in ventral aspect, 17

9. Daspletosaurus torosus , reconstruction of skeleton, 17

viii

Introduction

A small number of closely related genera of large theropodous saurischians is
known to have existed during late Cretaceous time in North America and
Central Asia. These reptiles, which may be termed tyrannosaurs, are noteworthy
for their large size (one form attained a length of 47 feet, perhaps weighing over
1\ tons in life; see Colbert 1962) and for their extreme adaptation to a carniv¬
orous mode of existence. Their remains indicate that they were completely
bipedal, as the lower segments of the hind limbs are proportionally longer than
in most other theropods, while the forelimbs are relatively quite small with only
two functional digits in the hand. The head is large and is lightly constructed,
the neck is short, and the pelvic region is very powerfully developed. The
premaxillary teeth are incisiform, as in carnivorous mammals, but the margins
of the long, deep muzzle are otherwise armed with sabre-shaped teeth. On this
continent the remains of tyrannosaurs have been recovered from sediments
deposited on flat deltaic plains bordering the western margin of the old interior
sea. They make up only a small percentage of the dinosaur specimens found in
these sediments in western Canada (Russell 1967); even so, more tyrannosaur
skeletal material has been collected here than in any comparable area of North
America.

The type skeleton of Albertosaurus libratus , from the Oldman Formation of
Alberta, has been thoroughly described and figured by Lambe (1917). Several
excellent specimens of this species, collected by the American Museum of
Natural History in Alberta, were also briefly described by Matthew and Brown
(1923). Lambe (1904) published a study of two incomplete skulls from the
Edmonton Formation, which Osborn later made the type and paratype of
Albertosaurus sarcophagus. A partial skeleton of this species, also from the
Edmonton Formation, has been described by Parks (1928). The youngest
species of the genus, A. lancensis , was established by Gilmore (1946) for a
partly crushed skull from the Lance Formation of southeastern Montana.
The osteology of Tyrannosaurus rex , from the Hell Creek Formation of Mon¬
tana, but also known from the Lance Formation of Wyoming (Gilmore 1920:
121-2), has been summarily described and well figured by Osborn (1905, 1906,
1912, 1913, 1917). For descriptions and figures of Tarbosaurus bataar from the
Nemegt beds of Mongolia see Maleyev 1955a, 19556, 1955c, 1964; Rozh¬
destvensky 1965.

A perusal of the above sources will show that the tyrannosaurs are a small
group of highly evolved, but nearly related forms. The author, in collaboration
with others, intends to speculate on their systematic position within the Thero-
poda elsewhere. The object of this paper is to characterize the Canadian forms
and to comment briefly on a few of the peculiarities of their morphology. Once
again I am very pleased to express my gratitude to Dr. Edwin H. Colbert of

the American Museum of Natural History for making tyrannosaur material
in the collections of that institution available to me for study. Dr. A. K.
Rozhdestvensky has generously forwarded data on Tarbosaurus specimens in
the collections of the Academy of Sciences of the U.S.S.R. To these gentlemen
and to Dr. Wann Langston, Jr., of the Texas Memorial Museum, I am indebted
for their courteous counsel on various problems concerning the structure of
tyrannosaurs. Special thanks go to Dr. A. G. Edmund of the Royal Ontario
Museum, and to Dr. R. C. Fox of the University of Alberta, for allowing me to
study tyrannosaur material in the collections under their care. As so often in
the past, Dr. C. M. Sternberg, Curator Emeritus of Fossil Vertebrates of the
National Museum of Canada, has rendered great assistance through his kindly
interest and in making available his great experience in collecting and studying
Cretaceous reptiles.

The following abbreviations of institutional names, which precede specimen
numbers referred to in the text, identify the place of storage of the specimen:
AMNH—American Museum of Natural History
BMNH—British Museum of Natural History
FMNH—Field Museum of Natural History

NMC —National Museums of Canada, Museum of Natural Sciences
ROM —Royal Ontario Museum
UA —University of Alberta

USNM—United States National Museum

*(Place)—assigned to species, though material insufficient for positive
identification.

Family TYRANNOSAURIDAE
Diagnosis

Premaxillary teeth reduced in size relative to those of maxilla, ‘U’-shaped in
cross-section with carinae bordering opposite edges of flat, posteriorly facing
surface. Three antorbital fenestrae within maxilla, anteriormost fenestra small
and inconspicuous in lateral aspect. Frontals narrow, parietals represented
dorsally as longitudinal crest of bone separating supratemporal fenestrae.
Supraoccipital enters dorsal border of foramen magnum, paroccipital processes
not depressed laterally. Laterosphenoids meet on midline of skull, separating
fenestra for optic nerve from ventroanterior opening of pituitary fossa. Spines
of cervical vertebrae most powerfully developed in anterior region of neck,
length of cervical centra seldom exceeds 10 per cent of that of femur. Length of
dorsal centra less than height of centrum. Length of humerus approximately
one-third that of femur, only two functional digits present in manus. The length
of the pubic boot in adults greater than half total length of pubis. Shaft of
ischium pointed distally, frequently with slight ventral recurvature toward tip.
Well-developed alae unite ischial shafts ventromedially. Lateral trochanter of
femur large, extends to proximal end of bone. The length of the tibia in adults
is about 90 per cent of that of the femur. Shaft of third metatarsal constricted
dorsally.

Comments

The family group name ‘Tyrannosauridae’ was proposed by Osborn (1906:
283) and is based on an unquestionably valid genus of carnivorous dinosaur
from the Hell Creek Formation of Montana. The family group name ‘Deino¬
dontidae’, which has often been used as a synonym of Tyrannosauridae, was
proposed by Cope (1866: 279, “Dinodontidae”), with Deinodon (Leidy 1857:
72; 1860: 143) as its type genus. The lectotype of Deinodon horridus (see Cope
1866: 279; Hay 1908: 359) consists of two fragmentary premaxillary teeth of
a large theropod from the Judith River Formation of Montana. No topotypic
specimens have ever been described from this formation. It has been suggested
(Hay 1908: 353; Matthew and Brown 1922: 374, 383) that Deinodon is con¬
generic with Gorgosaurus ( = Albertosaurus) from the Oldman and Edmonton
formations of southern Alberta. Gilmore (1946: 17) stressed the point that
this identity could not be demonstrated in view of the incompleteness of the
type teeth of Deinodon horridus and was inclined to doubt that the genus could
ever be satisfactorily defined.

Two genera of large carnivorous dinosaurs are now known to be present
(see below) in the Oldman Formation, a correlative of the Judith River Forma¬
tion across the International Boundary (L. S. Russell 1964: 13), and it is not
possible to distinguish them from each other or from Deinodon on the morphol¬
ogy of the premaxillary dentition. Deinodon horridus is evidently a nomen vanum .
Because it is not a useful systematic procedure to perpetuate family group
names based on generically unidentifiable material, Deinodontidae is rejected
in favour of Tyrannosauridae as an available family group name. The latter
name has recently gained widespread acceptance (see Colbert 1964; Walker
1964; Charig et al. 1965).

Gilmore (1946: 17) considered Dryptosaurus aquilunguis from the late
Cretaceous of New Jersey to be closely related to the large theropods of similar
age in the interior of North America and suggested that the family group name
‘Dryptosauridae’ (Marsh 1890: 424) would be available for them should
Deinodontidae prove to be based on an indeterminate type genus. In Dryp¬
tosaurus (for descriptions and measurements see Cope 1869-70: 100-08;
Huene 1932: 63-4) the manus is larger than in any known tyrannosaur. The
ungual phalanx of the first digit is very large, the length of its convex upper
surface amounting to 75 per cent of the total length of the humerus. In Dasple-
tosaurus , where the manus is relatively large for a tyrannosaur, this length is
approximately equal to only 40 per cent of the length of the humerus. The femur
in Dryptosaurus is very slender, and in contrast to conditions in a half-grown
tyrannosaur where the circumference /length ratio of the femur is comparable
(AMNH 5423), the tibia is distinctly shorter than the femur. It is unlikely that
additional material of Dryptosaurus will show that this genus and the western
forms should be placed in the same family.

Genus Albertosaurus Osborn 1905, p. 265

Gorgosaurus Lambe 1914, p. 13
Type species: Albertosaurus sarcophagus

Diagnosis

Premaxilla contacts nasal below external naris. Maxillary teeth relatively
smaller than in Daspletosaurus , posteriorly become more recurved and smaller
still. Anteriormost antorbital fenestra within maxilla visible in lateral aspect,
first antorbital fenestra longer than high. Nasals expand between lacrimals,
invaded posteromedially on either side by short broad tongue of frontal.
Frontal broadly exposed on skull roof, posteriorly recurved vertical cleft in
bone above orbit. Prefrontal either unexposed dorsally, or with small process
situated between lacrimal and frontal. Lacrimal ‘horn’ rectangular in lateral
aspect, with apex centred well in advance of antorbital ramus of bone; exceeds
postorbital ‘horn’ in development. Anteroexternal edge of antorbital ramus of
lacrimal curves anteroventrally across jugal, bounding pocket in jugal laterally.
Ventral process of ectopterygoid uninflated, with small ventrally opening sinus;
jugular process of bone similarly uninflated. Angular terminates posteriorly
behind surangular foramen.

Ventral openings of main basisphenoid sinus situated on either side of midline
of skull, dorsomedial to each basipterygoid process. Optic fenestra not bridged
medially by presphenoid. Cranial nerves III and IV exit separately on anterior
surface of laterosphenoid, although pit for III much larger than that of IV.
Exit for cranial nerve Vi situated close to anterolateral edge of laterosphenoid.

Neural spines of fourth and fifth cervicals subequal, broadly flattened laterally.
Spine of sixth cervical narrower, but does not come to point dorsally. Presacral
vertebrae tend to be longer and lower than in Daspletosaurus ; basal caudal
vertebrae diminish more rapidly in size posteriorly than in this genus.

The length of the humerus in adults is equal to about 30 per cent of that of
femur, forelimb lightly constructed. Anterodistal condyle of metacarpal I large,
causing first and second digits to be approximately parallel. First phalanx of
digit II slender in adults. Dorsal edge of ungual of digit I passes through arc
of about 120 degrees.

Anterior blade of ilium does not cover diapophysis of twelfth thoracic
vertebra. The circumference of the femur in adults is equal to 34 to 37 per cent
of the femur’s length. In comparison with Daspletosaurus specimens of similar
femur length, the presacral vertebral column is longer, thoracic ribs are slightly
shorter, forelimb is shorter, ilium and sacrum are shorter, and metatarsus is
slightly longer.

Comments

The generotypic species of Albertosaurus is based on two crania found at
different stratigraphic levels within the Edmonton Formation. These specimens
so closely resemble skulls referable to Gorgosaurus libratus , from the Oldman
Formation, that there can be little question of their generic identity. Gorgosaurus
is therefore considered as a junior synonym of Albertosaurus , and A. libratus
is in all probability the immediate ancestor of the Edmonton form. It has been

Figure 1—Albertosaurus libratus , reconstruction of the skull in lateral aspect, based primarily on a
photograph of FMNH PR308 (negative number 39115, courtesy of the American Museum
of Natural History), with the palate restored after AMNH 5336. The skull of FMNH
PR308 measures 1050 mm in length (Matthew and Brown 1923: 10).

suggested that interdental plates medial to the marginal dentition (Osborn
1905: 265; Lambe 1914: 14) and an intercoronoid (Lambe 1914: 14) are absent
in this genus, although this is not the case. Lambe (1914: 14; 1917: 16) has
emphasized the similarity of the first maxillary tooth in the type of A. libratus
to those in the premaxilla, considering this as characteristic of the genus. The
carinae of the anterior maxillary teeth of A. libratus (and of Daspletosaurus
also) are incipiently arranged as in the premaxillary teeth, and the number of
small anterior maxillary teeth is variable, ranging from none in FMNH PR 308
to two in AMNH 5664. Although it is partly crushed, the first maxillary tooth
of the type of A. libratus is probably not so premaxilliform as is indicated in
Lambe’s figure (1917, fig. 10B).

The dental formula of Albertosaurus is as follows: premaxillary teeth 4,
maxillary teeth 13-15, dentary teeth 14-16. There are 10-14 (in extreme cases 17)
serrations per 5 mm on the carinae of the marginal teeth, the serrations being
coarsest near the centre of the jaws and finest near the posterior end of the
jaws of immature individuals.

Albertosaurus libratus (Lambe 1914)

Gorgosaurus libratus Lambe 1914, p. 13
Gorgosaurus sternbergi Matthew and Brown 1923, p. 7

Distribution

Oldman Formation, near Steveville, Alberta.

Figure 2—Albertosaurus libratus , median elements of the skull roof restored after USNM 12814. The
area shown measures approximately 310 mm in length along the midline of the skull.

Referred specimens

*NMC 8782 incomplete manus and pes, fragments from hind limbs (3 miles
south of Steveville, upper half of beds).

*AMNH 5423 jaw fragments, four caudal vertebrae, fragments of pelvis,
left hind limb (Little Sandhill Creek basin).

NMC 2270 maxilla.

NMC 12063 maxilla.

ROM 4591 nasals (east side of coulee, at Denhart, Alberta).

AMNH 5664 (type of G. sternbergi) nearly complete skeleton (quarry 54 of
Sternberg 1950).

USNM 12814 nearly complete skeleton, lacking tail (Little Sandhill Creek
basin).

*NMC 2250 ilium.

ROM 1422 fragmentary skull.

ROM 1237 skeleton, lacking presacral vertebrae and right hind limb (quarry
21 of Sternberg 1950).

UA 10 skull, several presacral vertebrae and ribs, right humerus, left meta¬
tarsus (quarry 48 of Sternberg 1950).

AMNH 5432 left maxilla, left tibia-metatarsus and some phalanges of pes
(quarry 59 of Sternberg 1950).

NMC 11593 pelvis, hind limbs, base of tail (quarry 50 of Sternberg 1950).

ROM 683 maxillae.

ROM 436 left premaxilla and maxilla.

ROM 1247 palatal elements.

AMNH 5336 skull (quarry 57 of Sternberg 1950).

AMNH 5458 skull and nearly complete skeleton (Little Sandhill Creek basin).

NMC 2120 (type of G. librcitm) nearly complete skeleton (quarry 36 of
Sternberg 1950).

NMC 2193 surangular.

FMNH PR308 skull and skeleton, lacking hind limbs and tail (Little Sand¬
hill Creek basin).

NMC 11814 braincase.

Diagnosis

Length of dentary tooth row 71 per cent of length of fourth metatarsal
(USNM 128147, NMC 2120). In adult animals (NMC 2120) combined length of
scapula-coracoid greater than that of femur. In adult animals (AMNH 5458,
NMC 2120), combined length of tibia and astragalus 95 per cent of that of
femur.

Comments

Gorgosaurus sternbergi , with the most complete skeleton known of a North
American tyrannosaur as its type, was characterized by Matthew and Brown
(1923: 7) as follows: “It is of smaller size and more slender proportions that in
G. libratus. The jaws are much less massive and the muzzle is more slender, the
maxilla more elongate and shallow, the orbital fenestra more circular. The tibia
is considerably longer than the femur.” Gilmore (1946: 3) suggested that the
apparent slenderness of the muzzle in the type was caused by crushing, and
Rozhdestvensky (1965) has demonstrated that the tibia /femur ratio decreases
during growth in tyrannosaurs ( Tarbosaurus ).

Matthew and Brown (1923: 7) were aware of the possibility that these charac¬
ters might be due to the juvenility of the type specimen, noting that the pelvic
elements were not co-ossified. The sutures between the bones of the skull roof
are widely open, and there is nothing in the morphology of the specimen to
suggest that it is not an A. libratus approximately two-thirds grown. Interestingly,
the supraoccipital alae of the parietals are only about one-fourth as large as in
adults, indicating that these crests become more powerfully developed with
maturity.

Rozhdestvensky’s (1965) important studies of growth changes in the limb
proportions of Tarbosaurus require that North American material be examined
for similar growth effects. Although articulated remains of juvenile tyrannosaurs
are far from being the commonest of fossils, a barely adequate sample of half-
grown to adult specimens of A. libratus is available, from which some impression
may be gained of allometric growth in the species.

Six specimens of A . libratus from the badlands of the Oldman Formation
near Steveville, Alberta, have been examined for changes in bodily proportions
correlating with the size of the animal. The smallest individual of the series
AMNH 5423 was considered as possibly referable to A, libratus because the
lengths of the tibia and metatarsus continue the same trends seen in larger
specimens of the species, because Albertosaurus is three times as abundant as
Daspletosaurus in this area of outcrop of the Oldman Formation, and because
only adult specimens of the latter genus have so far been found here. The other
five specimens (AMNH 5664, USNM 12814, NMC 11593, AMNH 5458,
NMC 2120) have been assigned to A. libratus on the basis of their skeletal
anatomy (see diagnoses). The precise horizon from which each of these speci¬
mens was collected is known in only three cases, although dinosaurian fossils
are restricted to an approximately 200-foot vertical interval in the area (Stern¬
berg 1950). In view of the great resemblance of A. sarcophagus from the younger
Edmonton Formation to A. libratus , it is improbable that allometric changes
would be obscured by evolutionary changes over a stratigraphic interval of
this magnitude.

The length of the femur was arbitrarily chosen as a standard to which the
lengths of other skeletal structures in a specimen were compared (see Table 1).
The allometric changes are apparent when the lengths of the skeletal structures

Figure 3—Albertosaurus libratus , restoration of a hypothetical hatchling. The length of the femur is
100 mm.

Length Length 24 Length Length

Skull presacral Length caudal longest scapula- Length Length Length

-a

-C

•o

I I I

I I

I I I

o o

O ro
oo oo

I I I

I I

0 , s

oo *o
r- on
no r-

1 E 1

z z

NO ON
NO NO

ro Tt Zt _ 00
rt no 2S Tt o

V-J (O ^ ^

—' X ^
V Z U

< < D Z < Z

-c

aa^

§ 3

J £

c 3

<D X)

■s 2

W> < N<

g£

J H

•S O

S-S

*£ u o
aa 3 °

g a 7

h3 & w

pC £

aa .2
c x:

<o o
h4 .22

c x

<u 3

J a

ao g
G £
<u .2
-I T3

>5 ^

aa g
G O

>J £

1 Ss 1

O <o
«r> O
rO tJ-

0, ^ ~ .

s «0

"s'

^OOO^OrJ-
(N OO m OO (N ON
’t Tt IO in NO VN

I I I

h ^0\

. O Tf '"e' t NO

O w S w w
OD o' O © ©^
Tj- —« O ON o
t OO ON ON O

1 I I

o © Q <3

O NO NJ Nj
h OO O ^
<N

. rt
On O O

I I I

r- o
On —i

ON O

' i 1

m rf

Cf S oo Gv rt- O

3 Co ^ ^ ^

2 ao

«S?o

I I -S — I »N

z, z # o z o

<<DZ<Z

1 Measured from tip of snout to mandibular articulation.

2 Measured along outer curve from tuberculum to end (probably incorrectly estimated in AMNH 5664).

3 Measured from centre of iliac suture to anterior tip of pubic boot.

4 Measured from centre of iliac to distal end of ischium. lt _ _ . /in ,_

Measurements of AMNH 5664 and AMNH 5458 taken from Matthew and Brown (1923); those of NMC 2120 usually from Lambe (1917).

are expressed as a percentage of the femur length and plotted against femur
length on a graph. These data, although based on a minimal number of measure¬
ments, seem to indicate that as the animal increases in size from half-grown to
fully mature, the presacral vertebral column, ribs, scapula-coracoid, pubis,
and ischium increase more rapidly in length than does the femur; the skull,
sacrum, humerus, and radius-ulna grow at approximately the same rate; and
the caudal vertebral column, manus, tibia, metatarsus, and pes grow at a
slower rate. These relative rates of growth appear to be rather constant, although
in the case of the combined length of the tibia-astragalus the rate of increase is
slow, relative to that of the femur, until the animal attains the size of USNM
12814, when the growth rate abruptly changes to equal that of the femur.

The comparative changes in the proportions of skeletal structures may have
been of the same general magnitude during the earlier, more rapid stages of
growth. Assuming that this was true, it would be possible to estimate the relative
bodily proportions of a very young (hatchling) Albertosaurus Iibratus. For a
femur length of 100 mm, the lengths of the following structures were estimated
graphically as follows: skull 88 mm, presacral vertebral column 210 mm,
sacrum 70 mm, anterior twenty-four caudal vertebrae 390 mm, scapula-coracoid
63 mm, humerus 26 mm, ulna 20 mm, manus 48 mm, second metacarpal 7 mm,
ilium 100 mm, pubis 68 mm, ischium 54 mm, circumference of femur 28 mm,
tibia-astragalus 140 mm, metatarsal three 85 mm, third digit of pes 56 mm.

Using these figures as a guide, an attempt has been made to reconstruct the
skeleton of a hatchling tyrannosaur. The adult morphology of A. Iibratus has
been modified by reducing the development of muscle scars and tuberosities,
and the number of teeth in the jaws and by increasing the size of the orbit. The
ungual phalanges of the manus and pes are shown, as in a very immature speci¬
men (NMC 8782), referred to A. Iibratus because the first ungual of the manus,
unlike in Daspletosaurus , is strongly curved. The lengths of the ribs are entirely
conjectural, as the increase in rib length is apparently too rapid in more mature
individuals to have been sustained throughout the ontogeny of the animal. It
is hoped that this reconstruction (Figure 3) will serve both as an estimation of
the actual appearance of a very young specimen of A. Iibratus , and as a means
of focusing attention on misinterpretations unknowingly incorporated into it.

Albertosaurus sarcophagus Osborn 1905
Laelaps incrassatus , Cope 1892, p. 240
Dryptosaurus incrassatus , Lambe 1904, p. 6
Albertosaurus sarcophagus Osborn 1905, p. 265
Albertosaurus arctunguis Parks 1928, p. 7

Distribution

Lower Edmonton Formation, Red Deer River, Alberta.

Referred Specimens

NMC 5601 (paratype of A. sarcophagus) skull and lower jaws, fragments of
sacral vertebrae and ilium, distal end of tibia with astragalus, fourth
metatarsal, three ungual phalanges of pes (sec. ?, tp. 33, rge. 22, W. 4th
mer., east bank of Red Deer River, Member B of Edmonton Formation).

AMNH 5222 scattered skull (sec. 12 ?, tp. 33, rge. 22, W. 4th mer., 150
feet above east bank of Red Deer River, Member B of Edmonton Forma¬
tion).

ROM 807 (type of A. arctunguis) sacrum and adjacent vertebrae, left scapula-
coracoid and forelimb, left half of pelvic girdle and associated hind limb
(sec. 27 or 34. tp. 30, rge. 21, W. 4th mer., 100 feet above west bank of Red
Deer River, Member A of Edmonton Formation).

NMC 5600 (type of A . sarcophagus) palatal region of skull, braincase and
lower jaws (sec. 11 ?, tp. 29, rge. 21, W. 4th mer., approximately 100 feet
above Red Deer River, along Kneehills Creek, Member A of Edmonton
Formation).

?NMC 2196 scapula-coracoid, abdominal ribs (sec. 35 ?, tp. 28, rge. 20,
W. 4th mer., west bank of Red Deer River, Member A of Edmonton
Formation).

Diagnosis

Length of dentary tooth row 65 per cent of length of fourth metatarsal
(NMC 5601). In adult animals (ROM 807, if the distal end of the scapula has
not been broken off) combined length of the scapula-coracoid about 80 per
cent of that of femur. In adult animals (ROM 807) combined length of tibia
and astragalus equal to (or slightly greater than) that of femur.

Comments

In defining Albertosaurus arctunguis , Parks (1928: 5-7) stressed the dissi¬
milarities between the distal end of the fourth metatarsal of his specimen
(ROM 807) and that of the paratype of A. sarcophagus (NMC 5601). The
slightly pathologic condition of this portion of the latter element, as Parks
himself noted (1928: 7), accounts for some of the differences, while the remainder
are due to the fact that the posteroexternal edge of the distal articulating surface
has been broken off, which Parks failed to recognize. The ungual phalanges
associated with NMC 5601, considered by Parks as belonging to the manus,
actually belong to the pes. Altogether, it is not possible to separate the type of
A. arctunguis from the type and paratype of A. sarcophagus on morphological
grounds, and the great resemblance of each of these specimens to the corres¬
ponding region of the skeleton of A. libratus argues convincingly for their
inclusion within a single species.

In addition to the characters noted in the diagnosis, the forelimb of ROM
807 seems to be slightly shorter than in A. libratus (NMC 2120), and the pubis
is slightly larger than in the latter specimen ( see Parks 1928: 12, 20, 23). A .
sarcophagus occurs in both member A and B of the lower Edmonton Formation
(Russell and Chamney 1967: 10, 12). It is unfortunate that the species is not
known from more complete material.

In tyrannosaurs, the bone beneath the brain stem gives the appearance of
being solid. However, this region of the skull is almost entirely filled with large
sinuses, which are separated from one another only by thin walls. Fenestrae,
through which these sinuses communicate with the surface of the bone, have
occasionally been confused with openings for nerve or blood vessel conduits
(see for example Lambe 1904: pi. 7, fig. 15; Gilmore 1946: 10). A reconstruct

BPT

Figure 4 — Albertosaurus , reconstruction of the lower half of the
braincase seen in sagittal section. Abbreviations: CC
carotid canal, MED medullary cavity, PIT pituitary
fossa, ST sella turcica, VI hypothetical course of sixth
cranial nerve. For further explanation see text.

tion of the ventral part of the braincase in Albertosaurus is presented here
(Figure 4), based primarily on a partial dissection of the braincase of NMC 5600
(A. sarcophagus ), with the parasphenoidal area restored from ROM 1237
(A. libratus). The large sinuses located in the parasphenoid rostrum and ventral
part of the basisphenoid are seen in sagittal section. Dotted lines show the
approximate extent of the latter sinus and two other sinus systems on either
side of the cranial midline. The fenestrae linking each sinus system with the
exterior are indicated by arrows; the arrow labelled “X” passed through the
fenestra draining the sinus system in the paroccipital process. The more dorsal
sinus systems are partly subdivided by thin webs of bone, which would probably
exhibit a high degree of variability in different individuals.

In Tyrannosaurus (AMNH 5117), and also in Allosaurus (Osborn 1912: figs.
9-10), there is a foramen in the basisphenoid near the anteroventral edge of the
laterosphenoid, which Osborn identified as the ventroposterior opening of the
carotid canal. Although the distal part of the canal was not observed in NMC
5600, a small foramen in the pituitary fossa may mark its anterior termination.
Behind this is another foramen, which may have contained the sixth nerve.

Neither the posterior course of the canal leading to the latter foramen nor the
point of penetration of the sixth nerve into the floor of the medullary cavity
was identified in this specimen. Not shown in Figure 4 are the conduits for
nerves X to XII, which lie in the bone immediately ventrolateral to the medullary
cavity and emerge on the occipital face of the skull in three foramina situated
beside the neck of the occipital condyle. A small rod of bone, measuring 30 mm
between its broken ends and 2.5 mm in diameter, was found in the matrix
between the broken right quadrate and paroccipital process in NMC 5600. No
doubt it is the stapes.

Figure 5 —Semidiagrammatic relationships between the exits for cranial nerves Il-Vi on the anterior
surfaces of the orbitosphenoid and laterosphenoid. A. Albertosaurus libratus , after NMC
11814; B. Daspletosciurus torosus , after NMC 8506.

It should be noted that in tyrannosaurs the median elements of the dermal
skull roof are solidly sutured to each other and to the braincase below. This
rigidity, coupled with the structural weakness of the basipterygoid processes,
absolutely precludes any possibility of normal kinetic movement in the skull.
Perhaps the diarthroid joint between the quadrate and squamosal, loose over¬
lapping of the basipterygoid processes by the pterygoids, and split nature of
the posterior part of the palate would allow some displacement of the temporal
muscle mass in a medial direction. In similar fashion, the loose dorsal and
posterior contacts of the jugal and quadratojugal, in combination with a verti¬
cally flexible antorbital lacrimal bar, may have allowed some displacement of
the temporal muscle mass in a lateral direction. It is probable, however, that
these suites of structures operated in an entirely passive manner, in response to
the struggles of a massive prey held between the jaws. Even movements of the
postulated kind must have been very limited, serving only to prevent the
breakage of bones within the skull.

Genus Daspletosaurus new

Dasp/etosaurus torosus new species*

Distribution

Oldman Formation, near Steveville, Alberta, except where noted.

♦Etymology Dasplet , Gr., frightful; sauros y Gr., lizard, torosus , fleshy, with reference to the large
body.

Type

NMC 8506 skull and skeleton, lacking hind limbs (quarry 88 of Sternberg
1905).

Pcircitype

AMNH 5438 sacrum and adjacent thoracic and caudal vertebrae, pelvis,
right femur, left tibia and second metatarsal (Little Sandhill Creek basin).

Referred Specimens

NMC 350 left hind limb (sec. 31, tp. 20, rge. 11, W. 4th mer.).

AMNH 5346 maxilla (Little Sandhill Creek basin).

UA 11 right femur and fourth metatarsal.

NMC 11594 incomplete, weathered skull and lower jaws (Oldman Formation,
near Manyberries, Alberta: near centre NW.£ sec. 36, tp.l, rge. 6, W. 4th
mer., about 30 feet below prairie rim or 3,285 feet above sea level).

BMNH R4863 premaxilla, maxilla, dentary.

Diagnosis

Premaxilla does not contact nasal below external naris. Maxillary teeth large,
not greatly reduced posteriorly. Anteriormost antorbital fenestra within maxilla
minute, hardly visible in lateral aspect, first antorbital fenestra nearly as high
as long. Nasals slightly constricted between lacrimals, invaded posteriorly on
either side by long slender tongue of frontal. Frontal broadly exposed on skull
roof, lacks deep vertical cleft above orbit. Prefrontal broadly exposed dorsally
between nasal, lacrimal, and frontal. Lacrimal ‘horn’ triangular in lateral aspect,
with apex centred above antorbital ramus of bone; exceeds postorbital ‘horn’ in
development. Anteroexternal edge of antorbital ramus of lacrimal is not con¬
tinued across lateral surface of jugal. Ventral process of extopterygoid inflated,
with large ventrally opening sinus; jugular process of bone also inflated. Angular
terminates posteriorly beneath centre of surangular foramen.

Ventral opening of main basisphenoid sinus situated on midline of skull,
behind transverse wall linking basipterygoid processes. Optic fenestra not
bridged medially by presphenoid. Exits for cranial nerves III and IV contained
in single pit on anterior surface of laterosphenoid. Exit for cranial nerve \\
situated on lateral surface of laterosphenoid.

Neural spine of fourth cervical vertebra much larger than that of fifth. Neural
spine of fifth cervical distally pointed, that of sixth cervical smaller and sharply
pointed. Presacral vertebrae tend to be shorter and higher than in Albertosaurus ;
basal caudal vertebrae diminish less rapidly in size posteriorly than in latter
species.

In adults length of humerus estimated to equal 38 per cent of that of femur,
forelimb powerfully developed relative to that of Albertosaurus . Anterodistal
condyle of metacarpal I reduced, causing first digit to diverge distally from
second. First phalanx of digit II robust in adults. Dorsal edge of ungual of
digit I passes through arc of about 90 degrees.

Anterior blade of ilium covers diapophysis of twelfth thoracic vertebra. In
adults circumference of femur equal to 38 to 41 per cent of length of femur.
In comparison with Albertosaurus specimens of similar femur length, presacral
vertebral column is much shorter, thoracic ribs are slightly longer, forelimb is
longer, ilium and sacrum are longer, and metatarsus is slightly shorter.

Figure 6—Daspletosaurus torosus , reconstruction of the skull in lateral aspect, based on NMC 8506.

The foramen in the quadratojugal is taken from NMC 11315, where the element is better
preserved.

Comments

The type specimen of D. torosus was collected by C. M. Sternberg late in the
1921 field season. As is usual in large theropod specimens, the head and anterior
part of the vertebral column were pulled dorsoposteriorly toward the pelvis
before the animal was buried. Although the hind limbs and many of the more
distal caudal vertebrae were lost and although the remainder of the skeleton
was partly scattered, the specimen is generally very complete and very well
preserved. Sternberg’s field notes indicate that at the time the specimen was
collected he thought it belonged to an undescribed species of Gorgosaurus or
to a new genus. Photographs of the skeleton in situ have been published by
Sternberg (1945: 191; 1946: pi. 15; 1966: fig. 9), and of the skull by Sternberg
(1945: 191; 1946: pi. 6; 1966: fig. 17).

Figure 7—Daspletosciurus torosus , reconstruction of the skull in dorsal aspect, based on NMC 8506.

Daspletosaurus attained approximately the same length (28-30 feet) as its
contemporary Albertosaurus. However, the body, which measured 1,350 mm
(53 inches) through the widest point of the thoracic region in NMC 8506, and
the base of the tail are much heavier than in Albertosaurus , and the hips and
hind limbs are also more powerfully developed. The forelimb, although small,
is relatively larger than in any other known tyrannosaur. Interestingly, with the
exception of NMC 350, which is subadult, only fully grown specimens of
Daspletosaurus have so far been collected from the Oldman Formation, while
remains of one-half to three-quarters grown albertosaurs are relatively not
uncommon in these sediments. The simultaneous existence of these two large
carnosaurs indicates the presence in the fauna of two ecologic niches to accom¬
modate them. As the endocranial cavities of both forms are quite small, it
might be expected that differences in their gross morphology would rather
accurately express their behavioural differences. Perhaps the more powerfully
constructed daspletosaurs preyed on ceratopsians, and the more fleet alberto¬
saurs were better suited to subsist on hadrosaurs. Albertosaurs and hadrosaurs
are indeed correspondingly more abundant in the Oldman fauna than are
daspletosaurs and ceratopsians.

The reconstruction of Daspletosaurus torosus (Figure 9) is based principally
on the type skeleton (NMC 8506) and the hind limb of the paratype (AMNH
5438). Restored parts include the last two phalanges of the second digit of the
manus, acetabular area of the ischium, posterior tip of the pubic boot, all of
the metatarsals except the second, the entire pes, and caudal vertebrae 12-14,
18, 19, 21, 22, 26, 28-30, 32, and 36-37. The hind limbs of NMC 350 and
NMC 11594 were consulted in drawing elements missing in this region of the
type and paratype. Cervical and thoracic ribs are preserved on one side or the
other throughout the presacral series of NMC 8506. In the reconstruction
they are drawn as seen in lateral aspect, causing the ribs of the posterior thoracic
region, which curve away from the vertebrae at a high angle, to appear un¬
usually short. The solid line representing the ventral limit of the body was
obtained by projecting the curvature of the anterior thoracic ribs to the midline

of the body and by extending this line back to the anteroventral tip of the pubic
boot. The abdominal ribs are not shown in the reconstruction.

Figure 8—Daspletosaurus torosus , reconstruction of the skeleton. The length of the femur is 1000 mm,
for further explanation see text.

The dental formula of D. torosus , as indicated by cranial material referred
to the species, is: premaxillary teeth 4, maxillary teeth 14 or 15, dentary teeth
15 or 16. There are Ilf to 15 serrations per 5 mm on the carinae of the marginal
teeth, the serrations being coarsest near the centre of the jaws.

Figure 9—Daspletosaurus torosus , reconstruction of the palate in ventral aspect, based on NMC 8506.

The palate is disarticulated but exceptionally well preserved in NMC 8506
(see Figure 8). The vomers are fused together anteriorly dividing posteriorly
into two thin vertical sheets of bone. A vertical anterior ala from the pterygoid
broadly underlaps each of these vomerine processes. However, the pterygoids
do not meet each other on the midline of the skull, nor do they contact the

ventral part of the ascending processes of the palatines (the same relations
exist in the palate of A, libvatus , see AMNH negative number 37883, taken of
USNM 12814). In Albertosaurus (see NMC 5600; Gilmore 1946: 11) and prob¬
ably also in Daspletosaurus (NMC 8506) the upper edges of the anterior
pterygoid alae loosely but widely contact the upper edge of these palatine
processes, with the result that each half of the tyrannosaur palate is separated
from the opposite half as far anteriorly as the middle of the vomers. The
anterodorsal tip of the ascending process of the palatine is firmly applied to
the external dorsoposterior corner of the vomer in D. torosus (NMC 8506)
and perhaps also in Albertosaurus (AMNH 5336?; Gilmore 1946: 11).

Daspletosaurus cf. D. torosus

Distribution

Member B of Edmonton Formation, near Scollard, Alberta.

Referred Specimen

NMC 11315 scattered cranial elements, abdominal ribs, left forelimb, pelvis
and hind limbs (SW. f sec. 20, tp. 34, rge. 21, W. 4th mer., 150 feet above
south bank of Red Deer River).

Comments

NMC 11315 represents the remains of a slightly more than half-grown
tyrannosaur. It is referred to Daspletosaurus because the humerus, radius-ulna,
ilium, and circumference of the femur are longer relative to the length of the
femur than would be expected in an Albertosaurus of similar femur length. The
claw of the first digit of the manus seems less recurved than in the latter genus.
The specimen shows that Daspletosaurus probably underwent the same onto¬
genetic changes in limb proportions as did Albertosaurus . The foot is very
similar to that of Albertosaurus , although the metatarsus is slightly shorter
than in similarly sized specimens of this genus.

Tyrannosaur humeri are very infrequently found, and of the two Daspleto¬
saurus specimens where it is preserved, the distal end of one (NMC 8506) is
pathologic. Similarly, of five specimens of A. libratus where a humerus is
preserved, in two of them (UA 10, FMNH PR308) the bone has also been
damaged in life. This is an unusually high incidence of damage and suggests
that the small forelimbs were often crushed by the weight of the massive bodies
of these reptiles.

Genus Tyrannosaurus Osborn 1905, p. 259
Type species: Tyrannosaurus rex

Diagnosis {See Osborn 1906, 1912, 1917; Matthew and Brown 1923)

Premaxilla contacts nasal below external naris. Maxillary teeth relatively
larger than in Daspletosaurus. Anteriormost antorbital fenestra within maxilla
not visible in lateral aspect, first antorbital fenestra slightly higher than long.
Nasals narrowly constricted between lacrimals. Frontal essentially limited to
anteromedial wall of supratemporal fenestra, only small rim of bone reaches

dorsal surface of skull. Prefrontal exposed dorsally between lacrimal and
frontal. Lacrimal ‘horn’ represented by conical inflation not interrupting dorsal
profile of skull. Postorbital ‘horn’ or rugose area well developed. Antero-
external edge of antorbital ramus of lacrimal not continued across lateral
surface of jugal. Ventral process of ectopterygoid inflated with very large,
ventrally opening sinus. Angular terminates posteriorly behind surangular
foramen.

Ventral openings of main basisphenoid sinus situated on either side of midline
of skull, dorsomedial to each basipterygoid process. Vertical plate of presphe¬
noid contacts orbitosphenoid and narrow suboptic bridge of Iaterosphenoid,
separating optic fenestra into two openings. Cranial nerves III and IV open into
single pit ventrolateral to optic fenestra. Exit for cranial nerve Vj situated close
to anterolateral edge of Iaterosphenoid, but not so close as in Albertosaurus.

Neural spines of fourth and fifth cervical vertebrae subequal, rather narrow in
lateral aspect. Neural spine of fifth cervical distally pointed, that of sixth verte¬
bra smaller and sharply pointed. In adults length of humerus equal to about 28
per cent of that of femur. Anterior blade of ilium does not cover diapophysis of
twelfth thoracic vertebra. In adults circumference of femur approximately equal
to 41 per cent of length of femur. Bodily proportions generally as in Dasple-
tosaurus, although adult specimens about 25 per cent larger, humerus more
reduced and ilium longer than in this genus.

cf. Tyrannosaurus rex
Distribution

Upper Edmonton Formation, Alberta.

Referred Specimens

NMC 9950 phalanx of pes (7 miles east of Huxley, centre sec. 10, tp. 34, rge.
22, W. 4th mer., about 170 feet above Kneehills Tuff).

NMC 9554 fragment of cervical centrum (20 feet below and 200 yards south
of locality for NMC 9950).

Comments

The presence of Tyrannosaurus in Lance equivalent upper Edmonton strata
has been noted several times (see Sternberg 1949; L. S. Russell 1964; Langston
1965). This record is based primarily on a badly eroded and shattered skeleton
observed by Sternberg in 1946, weathering out of a fractured concretion high on
the face of a cliff. Langston revisited the locality in 1960 and collected a pha¬
lanx, noting that the skeleton was even more badly damaged than when Stern¬
berg discovered it, and that little of it still remained in situ.

The phalanx (NMC 9950) is the fourth one of the fourth toe and measures
53 mm in length and about 80 mm across its distal articulation. Hence it is
larger and broader than the corresponding element in Albertosaurus and Dasple -
tosaurus. Unfortunately only the first phalanx of the fourth toe is known in
Tyrannosaurus (Osborn 1906: fig. 11). This bone is relatively broader than in
any known Oldman or Edmonton form, and by analogy it seems probable that

the above fourth phalanx may indeed belong to Tyrannosaurus. The vertebra
(NMC 9554) is generically indeterminate.

TYRANNOSAURS NOT KNOWN TO OCCUR IN CANADA
Albertosaurus lancensis (Gilmore)

Gilmore (1946) has described the skull of a small carnivorous dinosaur from
the Lance Formation of eastern Montana. The skull is quite different from that
of Tyrannosaurus and Gilmore founded a new species on it, correctly referring
it to Gorgosaurus (= Albertosaurus). Although the skull is only half as long as
that of a fully grown A. libratus , the sutures between the bones of the skull roof
are tightly interlocking, and some have been obscured through intergrowth; the
supraoccipital alae of the parietals are well developed, and a clearly formed tu¬
berosity is present on the ventral border of the jugal (Gilmore 1946). The
opposite conditions prevail in the skull of AMNH 5664, a specimen of A.
libratus of comparable size. The skull of A . lancensis is therefore probably
from a fully grown individual, and its small size may be characteristic of the
species.

Albertosaurus lancensis further differs from A. libratus and A. sarcophagus
(AMNH 5222) in that the frontals meet on the midline throughout their entire
length, while in the latter two species these elements are separated anteriorly by
a small wedge of bone from the nasals. The frontals are not so deeply cleft
above the orbits as is the case in A. libratus and A. sarcophagus. Gilmore (1946:
6) suggested that the prefrontal may be rather well exposed on the skull roof,
unlike in the more ancient species of the genus. Otherwise the skulls of the
three forms are quite similar.

Tarbosaurus bataar (Maleyev)

This species is known from the remains of at least seven individuals collected
by the Palaeontological Institute of the Academy of Sciences of the U.S.S.R.
(Maleyev 19556, 1955c) and six more collected by the Polish-Mongolian
Palaeontological Expedition (Kielan-Jaworowska 1967), all from the Nemegt
basin in strata that may be approximately Edmontonian (see L. S. Russell 1963)
in age. The form has not yet been thoroughly described, although it has been the
subject of several brief reports (see Introduction) and a cast of the skull of one
specimen (NMC 10422) was available for study through an exchange with the
Palaeontological Institute. Tarbosaurus seems to be most closely allied to Tyran¬
nosaurus. It differs from this genus in that the nasals are not quite so constricted
between the lacrimals, the frontals do have some dorsal expression (but not so
much as in Albertosaurus or Daspletosaurus ), the surangular foramen is small,
and adult animals are smaller than adult specimens of Tyrannosaurus. (I am
indebted to Dr. A. K. Rozhdestvensky for the above information on the mor¬
phology of Tarbosaurus.)

TABLES OF MEASUREMENTS

All measurements are expressed in millimetres. The lengths of the phalanges
were measured between the lateral edges of the anterior and posterior articular
surfaces, along the horizontal midline of the bone.

MEASUREMENTS USNM 12814 Albertosaurus libratus
(see also Table 1)

SKULL:

Length lower dentition

352

DORSAL RIBS (tuberculum to end):

350

652

793

823

830

LENGTHS OF PHALANGES OF PES:

Right Pes

digit 1

digit 2

141

131*

digit 3

157

115*

digit 4

103

Left Pes

digit 1

digit 2

147

ca. 114*

digit 3

148

digit 4 ca.

For measurements of the type of A. libratus , see Lambe (1917). For measurements of specimens
of this species in the American Museum of Natural History, see Matthew and Brown (1923)

VERTEBRAE

Cervicals

Ant-post width

Height Anterior

Across Zygopophyses

Face of Vertebra

Length of Centrum

ca. 127

176

ca. 73

ca. 145

171

ca. 73

ca. 148

161

ca. 70

ca. 150

ca.157

ca. 82

ca. 145

175

ca. 87

ca. 123

183

ca. 110

197

ca. 105

198

Dorsals

Length of Centrum

Height of Vertebra

ca. 70

243

271

269

277

297

291

303

293

308

107

310

124

330

* Measured along dorsal curve of ungual.

MEASUREMENTS NMC 11593 Albertosaurus Ubratus
{see Table 1):

HIND LIMB:

length fibula 795

width astragalus 183

height astragalus 212

LENGTH OF ELEMENTS IN RIGHT PES:

metatarsal

digit 1

104

digit 2

520

172

digit 3

594

166

digit 4

123

112*

digit 5

LENGTH OF

ELEMENTS IN LEFT PES:

digit 1

109

digit 2

514

170

105

123*

digit 3

580

165

110

152*

digit 4

545

124

digit 5

223

CAUDAL VERTEBRAE:

Height of

Length of

vertebra

centrum

transverse

chevron

process

ca. 170

140

348

168

126

125

ca. 313

155

123

105

316

150

137

105

306

140

128

276

130

127

ca. 80

259

115

132

188

222

110

138

167

* Measured along dorsal curve of ungual.

MEASUREMENTS NMC 8506 Daspletosaurus torosits

SKULL:

Premaxilla—mandibular condyle 1040

Premaxilla—occipital condyle 1040

Supraoccipital crest'—mandibular condyle 450

Width across quadratojugals 425

Length upper dentition 530

Length lower dentition 420

Length lower jaw 1015/1020

Height muzzle above last maxillary tooth 300

Height of quadrate 248

DORSAL RIBS:

Length capitulum to Length tuberculum to end

tuberculum

left

right

left

right

ca. 210

237

—

617

243

257

868

252

265

997

254

263

1219

1212

262

264

1250

273

261

273

933

892

233

ca. 248

740

215

ca. 246

665

236

ca. 540

202

212

455

capitulum absent

465

FORELIMBS:

length of scapula

772

length of coracoid

170

length of humerus (pathologic)

357

length of ulna

214

length of radius

171

MANUS:

metacarpal

digit 1

133

155*

digit 2

120

digit 3

PELVIS:

length of ilium 1104

length of pubis 935 /902

* Measured along dorsal curve of ungual.

MEASUREMENTS NMC 8506 Daspletosciurus torosus

CERVICAL VERTEBRAE:
Ant-post Height
width across anterior face
zygopophyses of vertebra
1

2 160 300

3 150 290

4 165 285

5 187 280

6 175 260

7 175 273

8 135 305

9 135 338

10 118 ca. 345

*With axis intercentrum.
Total length of cervical series

DORSAL VERTEBRAE:

Length of
centrum

113

ca. 95

ca.112

104

ca. 110

ca. 118

ca. 108

ca. 118

ca. 108

Total length of dorsal series
Length of sacrum = 752.

CAUDAL VERTEBRAE:

Height of
vertebra

433

420

363

359

297

284

274

246

213

Height

Length

of centrum

ca. 60

110

80*

ca. 80

100

105

116

127

104

= 900.

Width of

Height of

centrum

138

140

ca. 138

124

126

145

127

136

125

140

ca. 120

ca. 123

ca. 154

127

ca. 128

ca. 178

ca. 138

1470.

Height of

Length of

centrum

ca. 140

195

151

165

134

160

133

145

ca.134

155

152

150

ca. 146

140

146

130

150

110

162

Width

across

of centrum

diapophyses

100

ca. 95

115

132

ca. 175

ca. 190

105

ca. 255

110

270

ca. 120

307

124

342

Height of

Width across

vertebra

diapophyses

356

332

340

290

348

282

372

276

405

293

415

295

430

308

440

292

458

278

282

308

454

313

447

Length of

transverse Length of
process chevron

ca. 205

ca. 170
ca. 165

ca. 160 252

ca. 130 248

ca. 118 242

ca. 115 204

ca. 118 188

ca. 75 174

ca. 88 162

MEASUREMENTS AMNH 5438 Daspletosaurus torosus

VERTEBRAE:

Dorsals Height

vertebra

11 434

12 467

Sacrals

Caudals

1 378

2 ca. 380
length of sacrum

Height Length

centrum centrum

168

100

ca. 183

118

ca. 175

143

ca. 173

132

ca. 125

ca. 133

165

173

174

113

ca. 174

712

PELVIS:

length of ilium 1096

HIND LIMB:

length of femur 1000

circumference of femur 390

length of tibia 870

length of metatarsal II 460

MEASUREMENTS UA 11 Daspletosaurus torosus

HIND LIMB:

length of femur

1000

circumference of femur

415

length of metatarsal IV

490

MEASUREMENTS NMC 11315 Daspletosaurus cf. D. torosus

SKULL:

height of quadrate

164

FORELIMB:

length of scapula

470

length of coracoid

110

length of humerus

225

length of ulna

120

length of radius

MANUS:

metacarpal

digit 1 32

digit 2 58

digit 3 38

PELVIS AND HIND LIMB:

length of ilium

ca. 675

length of pubis

ca. 600

length of pubic boot

365

length of ischium

488

length of femur

655

circumference of femur

226

length of tibia and astrag.

736

height of astragalus

233

width of astragalus

136/118

61*

LENGTH OF

ELEMENTS IN

RIGHT PES:

digit 1

metatarsal

1 2

digit 2

405

130 ca. 85

90*

digit 3

448

129 81

digit 4
digit 5

423

165

87 63

LENGTH OF

ELEMENTS IN

LEFT PES:

digit 1

digit 2

398

127

89*

digit 3

445

130

110*

digit 4

420

digit 5

165

Measured along dorsal curve of ungual.

References

Charig, A. J., J. Attridge, and A. W.
Crompton

(1965). On the origin of the sauropods
and the classification of the Saurischia.
Linnean Society of London Proceedings
176: 197-221.

Colbert, E. H.

(1962). The weights of dinosaurs.
American Museum of Natural History
Novitates 2076: 1-16.

(1964). Relationships of the saurischian
dinosaurs. American Museum of Natural
History Novitates 2181: 1-24.

Cope, E. D.

(1866). Remarks on dinosaur remains
from New Jersey. Academy of Natural
Sciences of Philadelphia Proceedings,
June, 1866: 275-279.

(1869-70). Synopsis of the extinct
Batrachia, Reptilia, and Aves of North
America. American Philosophical Society
Transactions n. s. 14: 1-252.

(1892). On the skull of the dinosaurian
Laelaps incrassatus Cope. American
Philosophical Society Proceedings 30:
240-245.

Gilmore, C. W.

(1920). Osteology of the carnivorous
dinosauria in the United States National
Museum. United States National Muse¬
um Bulletin 110: 1-159.

(1946). A new carnivorous dinosaur
from the Lance Formation of Montana.
Smithsonian Miscellaneous Collections
106(13): 1-19.

Hay, O. P.

(1908). On certain genera and species of
carnivorous dinosaurs, with special
reference to Ceratosaurus nasicornis
Marsh. United States National Museum
Proceedings 35(1648): 351-366.

Huene, F. von

(1932). Die fossile Reptil-Ordnung Sauri¬
schia, ihre Entwicklung und Geschichte.
Monographien zur Geologie und Palae-
ontologie 4: 1-361.

Kielan-Jaworowska, Z.

(1967). Les resultats des expeditions
paleontologiques polonomongoles (1963—
1965) dans le Desert de Gobi et Mon-
golie occidentale. Colloques Interna-
tionaux du Centre National de la
Recherche Scientifique, numero 163,
Problemes actuels de paleontologie: 419-
25.

Lambe, L. M.

(1904). On Dryptosaurus incrassatus
(Cope), from the Edmonton Series of
the North West Territory. Geological
Survey of Canada, Contributions to
Canadian Palaeontology 3: 1-27.

(1914). On a new genus and species of
carnivorous dinosaur from the Belly
River Formation of Alberta, with a
description of the skull of Stephanosaurus
marginatus from the same horizon.
Ottawa Naturalist 28: 13-20.

(1917). The Cretaceous theropodous
dinosaur Gorgosaurus. Geological Survey
of Canada Memoir 100: 1-84.

Langston, W., jr.

(1965). Pre-Cenozoic vertebrate pale¬
ontology in Alberta: its past and future.
In Vertebrate paleontology in Alberta,
University of Alberta, Edmonton, p. 9-
31.

Leidy, J.

(1857). Notices of remains of extinct
reptiles and fishes, discovered by Dr. F.
V. Hayden in the bad lands of the Judith
River, Nebraska Territory. Academy of
Natural Sciences of Philadelphia Pro¬
ceedings 8: 72-73.

(1860). Extinct Vertebrata from the
Judith River and Great Lignite Forma¬
tion of Nebraska. American Philoso¬
phical Society Transactions n. s. 11:
139-154.

Maleyev, E. A.

(1955«)- Carnivorous dinosaurs of Mon¬
golia (in Russian). Priroda June 1955:
112-115.

(1955/?). Gigantic carnivorous dinosaurs
of Mongolia (in Russian). Dokladi
Akademii Nauk S.S.S.R. 104(4): 634-
637.

(1955c). New carnivorous dinosaurs
from the upper Cretaceous of Mongolia
(in Russian). Dokladi Akademii Nauk
S.S.S.R. 104(5): 779-782.

(1964). Family Deinodontidae (in Rus¬
sian). In Rozhdestvensky, A. K. and L.
P. Tatarinov, Ocnovi Paleontologii 12:
538-540.

Marsh. O. C.

(1890). Additional characters of the
Ceratopsidae, with notice of new Creta¬
ceous dinosaurs. American Journal of
Science (third series) 39: 418-426.
Matthew, W. D., and B. Brown

(1922). The family Deinodontidae, with
notice of a new genus from the Creta¬
ceous of Alberta. American Museum of
Natural History Bulletin 46: 367-385.
(1923). Preliminary notices of skeletons
and skulls of Deinodontidae from the
Cretaceous of Alberta. American Mu¬
seum of Natural History Novitates 89:
1 - 10 .

Osborn, H. F.

(1905). Tyrannosaurus and other Creta¬
ceous carnivorous dinosaurs. American
Museum of Natural History Bulletin 21:
259-265.

(1906). Tyrannosaurus, upper Cretaceous
carnivorous dinosaur (second com¬
munication). American Museum of
Natural History Bulletin 22: 281-296.
(1912). Crania of Tyrannosaurus and
Allosaurus. American Museum of Natu¬
ral History Memoires (n. s.) 1: 1-30.
(1913). Tyrannosaurus , restoration and
model of the skeleton. American Mu¬
seum of Natural History Bulletin 32:
91-92.

(1917). Skeletal adaptations of Orni-
tholestes , Struthioniimus , Tyrannosaurus.
American Museum of Natural History
Bulletin 35: 733-771.

Parks, W. A.

(1928). Albertosaurus arctunguis , a new
species of therapodous dinosaur from
the Edmonton Formation of Alberta.
University of Toronto Studies, Geolo¬
gical Series 25: 1-42.

Rozhdestvensky, A. K.

(1965). Growth changes in Asian dino¬
saurs and some problems of their taxo¬
nomy. Paleontologicheskii Zhurnal 1965
(3): 95-109.

Russell, D. A.

(1967). A census of dinosaur specimens
collected in western Canada. National
Museum of Canada Natural History
Paper 36: 1-13.

-, and T. Potter Chamney

(1967). Notes on the bio-stratigraphy of
dinosaurian and microfossil faunas in
the Edmonton Formation (Cretaceous)
Alberta. National Museum of Canada
Natural History Paper 35: 1-22.

Russell, L. S.

(1964). Cretaceous non-marine faunas of
northwestern North America. Royal
Ontario Museum, Life Sciences Contri¬
bution 61: 1-24.

Sternberg, C. M.

(1945). Canadian dinosaurs. Canadian
Geographical Journal 30: 186-199.
(1946). Canadian dinosaurs. National
Museum of Canada Bulletin 103: 1-20.
(1949). The Edmonton fauna and de¬
scription of a new Triceratops from the
Upper Edmonton Member. National
Museum of Canada Bulletin 113: 33^46.
(1950). Map 969A Steveville west of the
fourth meridian, notes on fossil localities.
Geological Survey of Canada.

(1966). Canadian dinosaurs. National
Museum of Canada Bulletin 103 (second
edition): 1-28.

Walker, A. D.

(1964). Triassic reptiles from the Elgin
area: Ornithosuchus and the origin of
carnosaurs. Royal Society of London
Philosophical Transactions Series B
248: 53-134.

Plate I

Plate I—Albertosaurus libratus , AMNH 5664. The femur is 700 mm
long (Matthew and Brown 1923: 10). Photograph courtesy
of the American Museum of Natural History, AMNH
negative number 39016.

Plate II

Plate 11—Albertosaurus libratus , AMNH 5458. The femur is
approximately 1025 mm long (Matthew and Brown 1923:
10). Photograph courtesy of the American Museum of
Natural History, AMNH negative number 39106.

Plate III

Plate III—Daspletosaurus torosus , NMC 8506. Forelimb seen in
dorsal aspect.

Plate IV

Plate IV—DaspIetosaurus torosus , NMC 8506. Forelimb seen in
ventral aspect.

Internet Archive Audio

Featured

Top

Images

Featured

Top

Software

Featured

Top

Texts

Featured

Top

Video

Featured

Top

Mobile Apps

Browser Extensions

Archive-It Subscription

Save Page Now

Full text of "Tyrannosaurs from the Late Cretaceous of western Canada"

See other formats